• 한국해양공학회지
• /
• 제17권6호
• /
• pp.47-52
• /
• 2003

To determine the effect of transverse open crack on the dynamic behavior of simply-supported Euler-Bernoulli beam with the moving masses, an iterative modal analysis approach is developed. The influence of depth and position of the crack in the beam, on the dynamic behavior of the simply supported beam system, have been studied by numerical method. The cracked section is represented by a local flexibility matrix, connecting two undamaged beam segments that is, the crack is modeled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section, and is derived by applying a fundamental fracture mechanics theory. As the depth of the crack is increased, the mid-span deflection of the simply-supported beam, with the moving mass, is increased. The crack is positioned in the middle point of the pipe, and the mid-span defection of the simply-supported pipe represents maximum deflection.

• 한국정밀공학회지
• /
• 제22권1호
• /
• pp.143-151
• /
• 2005

This paper study the effect of open cracks on the dynamic behavior of simply supported Timoshenko beam with a moving mass. The influences of the depth and the position of the crack in the beam have been studied on the dynamic behavior of the simply supported beam system by numerical method. Using Lagrange's equation derives the equation of motion. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modeled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces on the crack section and is derived by the applying fundamental fracture mechanics theory. As the depth of the crack is increased the mid-span deflection of the Timoshenko beam with the moving mass is increased. And the effects of depth and position of crack on dynamic behavior of simply supported beam with moving mass are discussed.

• 한국소음진동공학회논문집
• /
• 제14권12호
• /
• pp.1295-1303
• /
• 2004

In this Paper a dynamic behavior of a cracked cantilever pipe conveying fluid with the moving mass is presented. It has the results focused on the response characteristics. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The cracked section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. When the fluid velocity is constant, the influences of the crack severity, the position of the crack, the moving mass and its velocity, and the coupling of these factors on the tip-displacement of the cantilever pipe are depicted.

• 한국소음진동공학회논문집
• /
• 제14권12호
• /
• pp.1304-1313
• /
• 2004

In this paper a dynamic behavior of a cracked cantilever pipe conveying fluid with the moving mass is presented. It has the results focused on the frequency change. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. When the velocity of the moving mass is constant, the influences of the crack severity, the position of the crack, the moving mass, and the coupling of these factors on the frequencies of the cantilever pipe are depicted.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1994년도 추계학술대회논문집; 한국종합전시장, 18 Nov. 1994
• /
• pp.238-243
• /
• 1994

본 논문에서는 여러가지 형태의 결합부에 적용할 수 있는 일반적인 모델링 기법에 대하여 기술하였다. 기존의 해석방법은 특정한 결합부에만 적용이 가능하고 유한요소해석과 실험이 상호 보완적인 관계를 가진 형태의 해석방법이므로 실험이 불가능한 경우에 대해서는 적용하기 어려운 경우도 있다. 본 논문에서는 별도의 실험을 수행하지 않고 결합부 영역만을 상세하게 유한요소 모델링을 하여서 선택된 자유도에 대한 유연성 행렬(Flexibility Matrix)을 구하여 결합부의 특성을 구하는 일반적 모델링 기법을 제시하였다. 이 방법은 수치적으로 축약할 수 없는 모델-결합부가 접촉면(Contact Surface)을 가지고 있는 구조물을 효과적으로 축약할 수 있는 장점이 있다. 또한 모델링되는 결합부의 경계조건의 영향을 배제할 수 있으며 결합부에 존재하는 비선형성도 적정범위내에서 선형화할 수 있다. 제시한 일반적 모델링 기법을 나사 결합부, 접착제 결합부(Glued Joints), 볼트 결합부에 적용하여 결합부이 특성을 구하였으며 실험을 통하여 제시한 해석방법의 타당성을 검증하였다.

• 대한기계학회논문집
• /
• 제18권6호
• /
• pp.1503-1509
• /
• 1994

An analysis method is suggested and experimentally studied in order to solve a vibration problem of a flexible structure while it is moving. In this method, substructure synthesis method, modal analysis method and Newmark's integral method were used. Total deformation of a structure was composed of quasistatic component and dynamic component. Rigid body modes were considered in calculation of dynamic component. Combining those two component, deformation behavior and a real structural model of a transfer feeder showed good agreements with computational results.

• 한국소음진동공학회논문집
• /
• 제15권10호
• /
• pp.1195-1201
• /
• 2005

In this paper, the effect of a moving mass on dynamic behavior of the cracked cantilever beam on elastic foundations is presented. Based on the Euler-Bernoulli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. That is, the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory The crack is assumed to be in the first mode of fracture. As the depth of crack is increased, the tip displacement of the cantilever beam is Increased. When the depth of crack is constant, the frequency of a cracked beam is proportional to the spring stiffness.

• 한국소음진동공학회논문집
• /
• 제15권4호
• /
• pp.483-491
• /
• 2005

In this paper a dynamic behavior of a double-cracked cantilever pipe with the tip mass and a moving mass is presented. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Lagrange's equation. The influences of the moving mass, the tip mass and double cracks have been studied on the dynamic behavior of a cantilever pipe system by numerical method. The cracks section are represented by the local flexibility matrix connecting two undamaged beam segments. Therefore, the cracks are modelled as a rotational spring. This matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. We investigated about the effect of the two cracks and a tip mass on the dynamic behavior of a cantilever pipe with a moving mass.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.799-804
• /
• 2004

In this paper a dynamic behavior of simply supported cracked simply supported beam with the moving masses is presented. Based on the Timoshenko beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics the of. And the crack is assumed to be in th first mode of fracture. As the depth of the crack and velocity of fluid are increased the mid-span deflection of the pipe conveying fluid with the moving mass is increased. As depth of the crack is increased, the effect that the velocity of the fluid on the mid-span deflection appeals more greatly.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집A
• /
• pp.631-636
• /
• 2000

In this paper a transfer method model was introduced in order to analyze critical speeds and vibration modes of a flexible rotor system, whose rotor shaft is cupped into and fitted with a thin-walled cylinder at its end. The computed analysis results were compared with those of the experimental modal test. Both results show good agreement each other. Furthermore the free-run(or run-down) test result for the real rotor system also shows that the proposed transfer matrix method modelling can be successfully applicable to analyzing accurate critical speeds(or natural frequencies) of the rotor system.